A magnetic metal-filled carbon nanocapsule is a polyhedral carbon cluster constituting multiple graphite layers having a balls-within-a ball structure with magnetic metals, metal compounds, metal, carbides or alloys therein. The diameter of a magnetic metal-filled carbon nanocapsule is about 3-100 nm. Magnetic metal-filled, carbon nanocapsules have special fullerene structure and optoelectronic properties. The magnetic metal nanoparticles therein is well-protected by the outer graphite layers from oxidation and acidic etching. Magnetic metal-filled carbon nanocapsules can be utilized in various fields such as medicine (medical grade active carbon), light and heat absorption, magnetic recording, magnetic fluids, catalysts, sensors, and nanoscale composite materials with thermal conductivity, special magnetic and electrical properties.
However, conventional methods for producing magnetic metal-filled carbon nanocapsules produce mainly single layer carbon nanotubes, but few carbon nanocapsules. Owing to the strong van der Waals force between carbon nanocapsules and nanotubes, it is not easy to separate the products. In addition, single layer carbon nanotubes have an end capped with metal particles of catalyst having magnetism as the magnetic metal-filled carbon nanocapsules, therefore magnetic attraction cannot be used for product separation. Conventional methods are not able to produce high purity magnetic metal-filled carbon nanocapsules, huge amounts of carbon ash impurities and single layer carbon nanotubes exist and lower the purity of products, increasing the cost. The related application on magnetic metal-filled carbon nanocapsules is limited and insufficient.